1893.] 



On certain Ternary Alloys. 



537 



with, lead, zinc, and cadmium, and the inner one (No. 2) that ob- 

 tained at 650 with bismuth, zinc, and tin (Part V). The position of 

 the limiting point L is deduced by Stokes's 2nd method, as that 

 where A + A' = 39 and B-f B' = 57, whence 



Bismuth 19'5 



Zinc o 28-5 



Cadmium 52*0 



100-0 



This corresponds with a ratio between bismuth and zinc close to 

 that indicated by the formula BiZn 5 ; the corresponding ratios pre- 

 viously found with tin and silver as solvent metals being respectively 

 close to BiZn 10 and BiZn 2 . 



The three points marked A, B, C, lying outside the critical curve, 

 represent the compositions of three mixtures that did not separate at 

 temperatures lying near to 600, the mean temperature correspond- 

 ing with the critical curve delineated ; on the other hand, the points 

 D and E, lying inside the critical curve, represent two mixtures that 

 did not separate when the temperature was somewhat raised (to near 

 650) ; showing that with mixtures of bismuth, zinc, and cadmium, 

 as with those of lead, zinc, and cadmium, a considerable depression of 

 the upper part of the critical curve is brought about by a compara- 

 tively slight elevation of temperature. 



On contrasting together the two critical curves thus obtained with 

 cadmium as solvent ifc is noticeable that in this case also the same 

 rule is observed as was found to hold in all the previously-described 

 cases, viz., that, ccBteris paribus, the substitution of bismuth for zinc as 

 the hea.vier of the two immiscible metals depresses the curve. As 

 regards the direction of slope of the tie lines, however, it is remark- 

 able that with cadmium as solvent the ties slope uniformly to the left 

 with lead, and to the right with bismuth, as the heavier immiscible 

 metal. With silver as solvent all ties slope to the left whether lead 

 or bismuth be the heavier immiscible metal, and whether zinc or 

 aluminium be the lighter one ; whilst with tin as solvent the opposite 



